Co-axial tuning tubes for muffler



May 19, 1970 F. R. HUBBELL m CO-AXIAL TUNING TUBES FOR MUFFLER FiledJuly 18, 1969 INVENTOR. 2/? f/Z z ZJz/(l. ,fl 2% United States Patent3,512,607 CO-AXIAL TUNING TUBES FOR MUFFLER Franklin R. Hubbell III,Brooklyn, Mich, assignor, by mesne assignments, to Tenneco Inc.,Houston, Tex., a corporation of Delaware Filed July 18, 1969, Ser. No.842,862 Int. Cl. F01n 1/02, 7/00 U.S. Cl. 181-48 2 Claims ABSTRACT OFTHE DISCLOSURE SUMMARY OF THE INVENTION It is the purpose of theinvention to simplify the structure used to form two resonator chambersof the type used in mufflers for attenuating sound in flowing gases. Theinvention achieves this by means of a one-piece tube which is formedwith different diameters and has an opening at the change of diametersection.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal cross section,partly schematic, of a typical internal combustion engine system exhaustmufller embodying the invention;

FIG. 2 is an enlarged view of the structure within the circle 2 of FIG.1; and

FIG. 3 is a section along the line 3-3.

DESCRIPTION OF THE INVENTION The mufller *1 has an oval shell 3 which isclosed at its inlet end by an inlet header 5 and its outlet end byheader 7, the headers having flanged openings 9 and 11. Within the shell3 are a series of longitudinally separated partitions 11, 13, 15, and 17which have outer annular flanges that are spotwelded to the shell. Thepartitions act with the end headers to define a series of axiallyadjacent chambers 19, 21, 23, 25, and 27.

An inlet bushing 29 is supported in the inlet header opening 9 and in asuitable annular flange 31 in the partition 11. Supported in thedownstream end of the bushing 29 is an inlet tube 33 which has itsdownstream end supported in an annular flange 35 in the partition [13.The partition 13 also supports by means of its annular flange 37 one endof a reverse flow tube 39, the other end of the tube being supported inan annular flange 41 in the partition 11. An outlet tube 43 has itsinlet end supported in an annular flange 45 in the partition 11 andextends through annular flanges 47 and 49 in the partitions 13 and 15.Its downstream end is supported in an outlet bushing 51 which in turn issupported in an annular flange 53 of the partition 17 and extends outthrough the flanged opening 11. The tubes 33, 39 and 43 may have louverpatches or openings 55, 57, and 59 in them to connect with chamber 21,as illustrated.

In accordance with this invention the chamber 23 is connected to thechambers 25 and 27 by a one-piece tuning tube member 61 having a largediameter section 63 and a small diameter section 65. The two sectionsare preferably coaxial. The shape of each is preferably circular, butone or the other or both may be of different shapes, such as oval orsquare. Preferably, the reduced diameter section 65 is formed by aswaging operation on a tube that is originally of the diameter ofsection 65. In reducing the diameter a wall 67 is formed which extendsradially with respect to the axis of the member 61 and it is providedwith a pair of openings 69 and 71 as best seen in FIG. 3. The tube 61 issupported in annular flanges 73 and 75 in the partitions 15 and '17 sothat the openings 69 and 71 communicate with chamber 25.

As is well known, the tuned frequency of a Helmholtz resonator is afunction of the volume of the tuning chamber (chambers 25 and 27) andthe conductivity of the tuning or feed tube .(tube 69) for the chamber.For the chamber 25 the conductivity is a function of the area andequivalent radius of feed openings 69 and 71, the length of tube section63, and the diameter of section 63. For chamber 27, the conductivity isa function of the lengths and diameters of both sections 63 and 65.These conductivities can be calculated and since the volumes of the twochambers is known it is apaprent that they can be tuned to attenuate twodifferent predetermined frequencies.

The rest of the mufiler functions in a known manner so that gas enteringinlet bushing 29 flows to the cross-over chamber 23 where it reversesits direction and passes by way of tube 39 to the chamber 19 wherereversal again occurs and the gas flows out of the mufller through tube43 and the outlet bushing 51. Silencing occurs because of the flowpattern and the expansion and contraction of the gas as well as by meansof the acoustic action of the hole groups 55, 57, and 59 with thechamber 21. Other silencing means may also be used, as desired, with thearrangement of tube 61 and chambers 25 and 27.

What is claimed is:

1. In a mufller for attenuating sound in flowing fluid, a housingincluding partition means defining three aligned but separate chambers,a one-piece tube having both ends open and supported in said partitionmeans, one end of the tube opening in a first of said chambers and theother end of the tube opening into a second of said chambers, the thirdof said chambers being located between the first and second, said tubehaving a first diameter portion and a second diameter portion smallerthan the first and a radial wall portion interconnecting the twoportions, said radial wall portion being located in said third chamberand being partially open to connect the first and third chambers throughthe first diameter portion of the tu e.

2. A muffler as set forth in claim 1 wherein the lengths and sizes ofthe two tube portions and the volumes of the second and third chambersare interrelated so that they are tuned to attenuate predetermined soundfrequencies.

References Cited UNITED STATES PATENTS 3,209,858 10/1965 Jettinghoff181-54 FOREIGN PATENTS Ad. 49,088 7/ 1938 France.

ROBERT S. WARD, JR., Primary Examiner U.S. Cl. X.R. 18154

